In the related art, as a restricting device, for example, a vehicle deflector device described in JP 2014-69615A (FIG. 5) (hereinafter, referred to as Reference 1) is known. An arm portion (wind-shielding end portion) of a deflector included in this vehicle deflector device has a restricting portion that is formed in a hole portion penetrating a center portion in a vertical direction and a buffer member (buffer portion) fitted to the hole portion. Thus, in an unfolded state of the deflector, the buffer member comes into contact with a lower protrusion portion provided in an opening edge of a roof opening portion. That is, the buffer member comes into contact with the lower protrusion portion and thereby a posture change of the deflector is restricted in the unfolded state. In this case, the buffer member is made of rubber and thereby it is assumed that an impact sound during the contact is suppressed.
However, in Reference 1, in order to prevent slip-off of the buffer member which is in the state of being fitted to the hole portion, a diameter of a tip portion of the buffer member penetrating the hole portion is enlarged substantially in an umbrella shape, and a latching margin is ensured between a peripheral edge portion of the hole portion and the tip portion of the buffer member. Therefore, it is necessary to reduce the diameter of the tip portion when fitting the buffer member to the hole portion during assembling the buffer member. Usually, it is difficult to press-fit the umbrella-shaped tip portion of the buffer member into the hole portion and it is necessary to pull the tip portion from a side opposite to the hole portion. Specifically, in formation of a protrusion in advance for pulling the tip portion of the buffer member, an operation, in which the tip portion is made to penetrate into the hole portion by pulling the protrusion and the protrusion is removed after fitting, is performed. Therefore, it is inevitable that the number of assembling man-hours for the buffer member will increase.